Molecular Lanthanide Switches for Magnetism and Photoluminescence

Solvation of [(CNT)Ln(η⁸-COT)] (Ln=La, Ce, Nd, Tb, Er; CNT=cyclononatetraenyl, i.e., C₉H₉⁻; COT=cyclooctatetraendiid, i.e., C₈H₈²⁻) complexes with tetrahydrofuran (THF) gives rise to neutral [(η⁴-CNT)Ln(thf)₂(η⁸-COT)] (Ln=La, Ce) and ionic [Ln(thf)_x(η⁸-COT)][CNT] (x=4 (Ce, Nd, Tb), 3 (Er)) species in a solid-to-solid transformation. Due to the severe distortion of the ligand sphere upon solvation, these species act as switchable luminophores and single-molecule magnets. The desolvation of the coordinated solvents can be triggered by applying a dynamic vacuum, as well as a temperature gradient stimulus. Raman spectroscopic investigations revealed fast and fully reversible solvation and desolvation processes. Moreover, we also show that a Nd:YAG laser can induce the necessary temperature gradient for a self-sufficient switching process of the Ce(III) analogue in a spatially resolved manner.     

Synthesis and catalytic application of chiral 1,1'-Bi-2-naphthol- and biphenanthrol-based pincer complexes: selective allylation of sulfonimines with allyl stannane and allyl trifluoroborate

New easily accessible 1,1'-bi-2-naphthol- (BINOL-) and biphenanthrol-based chiral pincer complex catalysts were prepared for selective (up to 85% enantiomeric excess) allylation of sulfonimines. The chiral pincer complexes were prepared by a flexible modular approach allowing an efficient tuning of the selectivity of the catalysts. By employment of the different enantiomeric forms of the catalysts, both enantiomers of the homoallylic amines could be selectively obtained. Both allyl stannanes and allyl trifluoroborates can be employed as allyl sources in the reactions. The biphenanthrol-based complexes gave higher selectivity than the substituted BINOL-based analogues, probably because of the well-shaped chiral pocket generated by employment of the biphenanthrol complexes. The enantioselective allylation of sulfonimines presented in this study has important implications for the mechanism given for the pincer complex-catalyzed allylation reactions, confirming that this process takes place without involvement of palladium(0) species.     

β-Sitosterol Circumvents Obesity Induced Inflammation and Insulin Resistance by down-Regulating IKKβ/NF-κB and JNK Signaling Pathway in Adipocytes of Type 2 Diabetic Rats

β-sitosterol (SIT), the most abundant bioactive component of vegetable oil and other plants, is a highly potent antidiabetic drug. Our previous studies show that SIT controls hyperglycemia and insulin resistance by activating insulin receptor and glucose transporter 4 (GLUT-4) in the adipocytes of obesity induced type 2 diabetic rats. The current research was undertaken to investigate if SIT could also exert its antidiabetic effects by circumventing adipocyte induced inflammation, a key driving factor for insulin resistance in obese individuals. Effective dose of SIT (20 mg/kg b.wt) was administered orally for 30 days to high fat diet and sucrose induced type-2 diabetic rats. Metformin, the conventionally used antidiabetic drug was used as a positive control. Interestingly, SIT treatment restores the elevated serum levels of proinflammatory cytokines including leptin, resistin, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) to normalcy and increases anti-inflammatory adipocytokines including adiponectin in type 2 diabetic rats. Furthermore, SIT decreases sterol regulatory element binding protein-1c (SREBP-1c) and enhances Peroxisome Proliferator–activated receptor-γ (PPAR-γ) gene expression in adipocytes of diabetic rats. The gene and protein expression of c-Jun-N-terminal kinase-1 (JNK1), inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ) and nuclear factor kappa B (NF-κB) were also significantly attenuated in SIT treated groups. More importantly, SIT acts very effectively as metformin to circumvent inflammation and insulin resistance in diabetic rats. Our results clearly show that SIT inhibits obesity induced insulin resistance by ameliorating the inflammatory events in the adipose tissue through the downregulation of IKKβ/NF-κB and c-Jun-N-terminal kinase (JNK) signaling pathway.     

Anisotropy models in precise crystallite size determination of mechanically alloyed powders

Nanocrystalline AA 4032 alloy powder was synthesized by high-energy ball milling from elemental powders for 30 h duration. XRD and TEM results reveal that the powder is cubic and nanocrystalline in nature. X-ray peak broadening analysis was used to evaluate the lattice strain and the crystallite size using the Williamson-Hall analysis with three different models viz., uniform deformation, uniform deformation stress and uniform deformation energy density. The root mean square (RMS) strain was calculated from the interplanar spacing and the strain estimated from the three models. The three models yield different strain values due to the anisotropic nature of the material. The energy density model is proposed to be the best fit model among the three as severe lattice strain is associated with ball milled powders.     

Adsorption of methylene blue dye from aqueous solution by agricultural waste: Equilibrium,thermodynamics, kinetics,mechanism and process design

The adsorption of methylene blue (MB) dye from aqueous solution onto a cashew nut shell (CNS) was investigated as a function of parameters such as solution pH, CNS dose, contact time, initial MB dye concentration and temperature. The CNS was shown to be effective for the quantitative removal of MB dye, and the equilibrium was reached in 60 min. The experimental data were analysed by two-parameter isotherms (Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models) using nonlinear regression analysis. The characteristic parameters for each isotherm and the related correlation coefficients were determined. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were also evaluated, the sorption process was found to be spontaneous and exothermic. Pseudo-first-order, pseudo-second-order and Elovich kinetic models were used to analyze the adsorption process. The results of the kinetic study suggest that the adsorption of MB dye matches the pseudo-second-order equation, suggesting that the adsorption process is presumably chemisorption. The adsorption process was found to be controlled by both surface and pore diffusion. Analysis of adsorption data using a Boyd kinetic plot confirmed that the external mass transfer is a rate determining step in the sorption process. A single-stage batch adsorber was designed for different CNS doses to effluent volume ratios using the Freundlich equation. The results indicated that the CNS could be used effectively to adsorb MB dye from aqueous solutions.     

A novel primary amine-based anion exchange membrane adsorber

A novel anion exchange membrane adsorber is presented which shows excellent impurity removal under different buffer conductivities ranging from 2 to 2 7mS/cm. The membrane utilizes a primary amine ligand (polyallylamine) and was designed specifically to bind impurities at high salt concentrations. Studies with DNA, endotoxin, and virus spiked into buffer at varying salt conditions were done, resulting in clearance of >3, 4, and 4 LRV, respectively, with negligible change on increasing salt up to 27 mS/cm conductivities. Verification of virus removal in mAb feedstocks is also shown. The data are compared with other membrane adsorbers and a conventional resin which utilize traditional chemistries to demonstrate improved purification performance with the primary amine ligand. Additional data on scale-up of the membrane adsorber device is discussed. A stacked flat-sheet design was implemented to ensure linear scale-up of performance using bovine serum albumin (BSA) as a model. The linearly scalable device, coupled with the highly effective membrane for virus, DNA, and endotoxin removal, represents a step forward in polishing technology for the purification of monoclonal antibodies and recombinant proteins.     

A facile stereoselective synthesis of julolidine hybrid analogs via domino knoevenagel intramolecular hetero Diels–Alder reaction

We have reported here a facile stereoselective synthesis of julolidine hybrid analogs by employing domino Knoevenagel intramolecular hetero Diels–Alder reaction on symmetrical 1,3-diones and unsymmetrical 1,3-diones It was found that the cycloaddition proceeded efficiently under microwave irradiation to afford highly stereoselective cycloadducts in good yields     

A novel water soluble ligand bridged cobalt(II) coordination polymer of 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (isonicotinic) hydrazone: evaluation of the DNA binding, protein interaction, radical scavenging and anticancer activity

A novel water soluble ligand-bridged cobalt(II) coordination polymer has been synthesized by reacting the new ligand, 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (isonicotinic) hydrazone (H(2)L) with Co(NO(3))(2)·6H(2)O and characterized by spectral, analytical and structural methods. Single crystal X-ray diffraction studies revealed that the Co(II) complex, {[Co(H(2)L)(H(2)O)(2)](NO(3))(2)·3H(2)O}(n) has a slightly distorted octahedral geometry around the central Co(II) ion; the ligand is coordinated through the ONO donor atoms to one Co(II) metal center and bridged through the pyridine nitrogen atom to another similar Co(II) center so as to form a one-dimensional polymeric unit. The interaction of the ligand and the complex with calf thymus DNA (CT-DNA) has been explored by absorption and emission titration methods, which revealed that the compounds could interact with CT-DNA through intercalation. The interactions of the compounds with bovine serum albumin (BSA) were also investigated using UV-visible, fluorescence and synchronous fluorescence spectroscopic methods. The results indicated that the complex exhibited a strong binding to BSA over the ligand. Investigation of the antioxidative properties showed that the polymeric Co(II) complex has a strong radical scavenging potency against hydroxyl radicals, 2,2-diphenyl-1-picrylhydrazyl radicals, nitric oxide and superoxide anion radicals. Further, the cytotoxic effect of the compounds examined on cancerous cell lines, such as human cervical cancer cells (HeLa), human laryngeal epithelial carcinoma cells (HEp-2), human liver carcinoma cells (Hep G2), human skin cancer cells (A431) and non-cancerous NIH 3T3 mouse embryonic fibroblasts cell lines showed that the complex exhibited substantial anticancer activity.     

Novel and efficient method for esterification catalyzed by 1-glycyl-3-methyl imidazolium chloride-iron (III) complex

1-Glycyl-3-methyl imidazolium chloride-iron (III) complex [[Gmim]Cl?CFe(III)] was found to be a heterogeneous catalyst for an efficient and greener solvent free synthesis of esters by the condensation of carboxylic acids and alcohols with excellent yield at ambient temperature. This operation formulates very interesting, ecological perspective due to simple reaction condition, isolation, and purification of products. In addition, this method features reusability of catalyst, reduced waste, thus making new protocol more environmentally suitable whilst no catalyst leaching was observed.